Format strings -fu: truncating/padding

[Jeremie Le Hen]

Hi list,

I've been using screen for a couple of years with a hardstatus string
stolen on the web and tinkled a bit afterward.  But now I'd like to
improve it.

Format escape sequences are fairly easy to understand (although
re-reading them is another thing ;p) except the truncation/padding
stuff.  I've tried to read and re-read the paragraphs about %=, %<
and %= multiples times but honestly, I can't grasp the way it works.

By browsing the web, it seems humans capable of mastering screen's
string escapes exist but they didn't bother explaining those thoroughly.

So my first question is: has a book (or more seriously an article or a
detailed post) ever been written on the subject?  Is yes, I'd be glad to
be pointed it out.

As a matter of fact, I'm trying to have a hardstatus string ressembling
this (I've left out the attributes/color modifiers):
    
    [%H] %-w (%n-%t) %+n [%d/%m %c]

But I'd like [%H] to be snugged against the left side and [%d/%m %c] the
be against the right one and the window list centered betweenthem.  I've
fumbled to get this and eventually more or less found a solution at work
by picking ideas here and there on the web:

    [%H]%= %-w (%n-%t) %+w %=[%d/%m %c]

But the icing on the cake would be the window list pushing neither left
or right but instead getting trimmed with the current window still in
the center.  But this I've never managed to make this up.

Thanks in advance for your help!
-- 
Jeremie Le Hen